1. Field of the Invention
The present invention relates to a theft prevention apparatus configured to prevent theft (defined to include a loss of a transmitter as well as theft in a general sense) of leisure vehicles such as motor vehicles including motorcycles, three-wheeled vehicles, and four-wheeled vehicles equipped with riders' seats which open outside, personal watercraft (PWC), etc.
2. Description of the Related Art
Typically, a motorcycle or personal watercraft, each of which is a type of leisure vehicle, is equipped with a rider's seat which is open to the outside. So, a rider may freely mount the rider's seat. During operation, in many cases a rider steers the vehicle wearing gloves. Therefore, it is difficult for the rider to take out a key from a pocket or the like with a hand wearing a glove.
When the rider comes closer to a predetermined distance away from the vehicle, a user identification (ID) code is transmitted from a portable transmitter put in the pocket or the like and is received by a receiver equipped in the vehicle. A controller built into the vehicle determines whether or not the received code matches a correct user ID code. If it is determined that the received code matches the correct user ID code, the controller configures the vehicle for a start-up condition, whereas if it is determined that the received code does not match the correct user ID code, the controller configures the vehicle to an unsteerable condition. Such a remote-controllable theft prevention apparatus is disclosed in Japanese Laid-Open Patent Application Publication No. 8-120992.
However, since leisure vehicles such as motorcycles or personal watercraft are equipped with a rider's seat which is open to the outside as described above, anyone can mount the seat. If the rider (owner) carrying the transmitter associated with the vehicle comes closer to a predetermined distance, for example, 10 meters away from the vehicle, then the user ID code matches the correct user ID code, so that someone riding on the seat, other than the rider (owner), may start-up an engine of the vehicle. As a result, there exists a chance of theft of the vehicle.
Furthermore, since the rider's seat is open to the outside as mentioned above, the transmitter may fall off of the pocket or the like and may be lost during travel of the vehicle. In that case, if the rider (owner) stops the vehicle and turns off a power supply of the vehicle at a gas station or the like, even the rider (owner) cannot start-up the vehicle again.